对籼稻标记基因系材料多蘖矮的遗传分析表明, 其矮生性状是由2对隐性半矮秆基因控制的,分别为sd1和一个新的半矮秆基因,该基因初步定名为sdt3。以多蘖矮与南京6号杂交F2的分离群体为基础，应用SSR标记进行连锁分析，将半矮秆基因sdt3定位于第11染色体的SSR标记SSR98和SSR35之间，分别相距0.06 cM、0.13 cM，二者之间的物理距离约为93kb。以南京6号为轮回亲本与多蘖矮进行回交和自交获得由半矮秆基因sdt3控制的近等基因系（新多蘖矮），以赤霉素处理表明由sdt3控制的半矮秆系新多蘖矮对赤霉素不敏感。
Evidence indicates high increases in rice yield due to semidwarf gene sd1 in rice. But the dwarf stature being used is controlled by a recessive semidwarf gene sd1, which can sometimes cause fragility of genetic resource and yield decrease. These problems associated with this gene have been necessitated identification and utilization of new and better dwarf genes. The marker line material Duonieai（DA） used in the study is a dwarf mutant , however genetic analysis showed that its dwarf trait was controlled by two recessive semidwarf genes, sd1 and a new semidwarf gene. F2 segregating population between Duonieai and Nanjing 6（N6）was established and SSR marker linkage analysis was performed on them. The new semidwarf gene was located between microsatellite markers SSR98 and SSR35 on chromosome 11, the genetic distances between them were 0.06 cM and 0.13 cM, respectively. Two BAC clones covering the two microsatellite markers had been sequenced with their full sequences being 154 kilobase and 156 kilobase, respectively. Also, 30 kilobase was overlapped between the two BAC clones. According to the sequence information on chromosome11 ,physical map revealed that few BAC clones were near the new semidwarf 93 kilobase, the new semidwarf gene could be delimitated within this 93 kilobase. The near isogenic line Xinduonieai（XDA）with the new semidwarf gene from a backcross between Nanjing6 and Duonieai was found insensitive to gibberellin.
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